This is a text from NHK easy news where the alcohol content of desinfectants is being discussed:


I am wondering here about the literal translation of the と-Particle in これより濃{こ}い消毒{しょうどく}する力{ちから}. Does the と-Particle in this case mean:

  • WITH higher (alcohol) concentration than this (the desinfection efficacy will be smaller...), or
  • IF the (alcohol) concentration is higer than this (the desinfection efficacy will be smaller...)

(So my question aims also a bit if this is how a proportionality relation, e.g. "with increasing speed the kinetic energy increases" can be expressed in Japanese)

Thanks a lot!

  • I think too strong alcohol contains less water to disinfect pathogen effectively (i.e. 70% concentration of alcohol works better than that of over 91%) . cf. This article : Why Is 70% the Most Effective Concentration of Isopropyl Alcohol for Disinfection?. It explains "The presence of water is a crucial factor in destroying or inhibiting the growth of pathogenic microorganisms with isopropyl alcohol..." Commented Apr 19, 2020 at 12:05
  • It wouldn't use と in any way, but which do you mean, "with increasing speed that the" or "with increasing speed, the..."? Commented Apr 19, 2020 at 12:10
  • 1
    This と can only mean 'if' here. The meaning of 'with' would be ungrammatical when と follows a predicate. Commented Apr 19, 2020 at 12:37
  • @broccolifacemask-cloth "with increasing speed(,) the kinetic energy increases" is equivalent to "as the speed increases, the kinetic energy increases". Commented Apr 19, 2020 at 12:40
  • 1
    @broccolifacemask-cloth As a physicist who understand the meaning of kinetic energy, for me there is only one natural meaning to this sentence. The sentence fragment "with (the) increasing speed that the kinetic energy increases" sounds rather awkward. You could massage it into a grammatical sentence, but it would have to be a pretty weird context, and I think there would be more natural ways to express it. Commented Apr 19, 2020 at 13:08

1 Answer 1


This is not explicitly expressing proportionality, it's just a conditional. Of course, constructions like this:


If the alcohol content is higher than this the disinfection efficacy will be smaller

In both English and Japanese do not exclude the possibility that there is a proportional relationship here between these two things, they just underspecify.

The thing most closely resembling the with you are asking about here, in terms of being relatively formal and expressing proportionality, is とともに. See here for some examples, like:


increase with prolonged therapy

Colloquially, proportional relationships can also be expressed with constructions like すればするほど.

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